Storage devices of this type are known in different embodiments and are used in particular also as buffer stores in installations for the processing and/or machining of products. Such storage devices comprise two transport elements arranged parallel to one another and side-by-side. The transport elements have opposed conveying or transport directions and form a transport surface on which the products stand or lie.
At one end of the transport surface, one of the transport elements forms a product entry through which the products are fed to the storage device or to its transport surface. The other transport element forms a product exit through which, in normal operation, the products are discharged out of the storage device or from the transport surface.
A transfer element is typically provided on the transport surface opposite the product entry and the product exit. The transfer element causes the products to be diverted or transferred from one transport element to the other. By adjusting the position of the transfer element with an actuating drive relative to the product entry or product exit, i.e. by changing the distance between the transfer element and the product entry/product exit, the storage or receiving capacity of the storage device or of the storage or buffer sections formed on the transport elements between the transfer element and the product entry/product exit can be varied and adapted to suit the particular requirements.
The transport elements are each formed by at least one transport belt that is driven to circulate in an endless loop. As a rule, there are two or more transport belts. The belts are arranged tightly adjacent to one another at least square to the transport direction.
In known storage devices of the afore-mentioned type, as described in EP 1 807 329 A1 and EP 1 632 445 A1, the transfer element is a passive element, i.e. an element that constitutes only one guide section or transfer section for the products and that consists in essence of a contact or sliding surface for the products. The transfer section, or its contact or sliding surface, extends over the full or essentially full width of the two transport elements and on the side facing the product entry and product exit is concavely arched about at least one axis square to the transport surface or to the transport plane defined by that transport surface.
It is a disadvantage of these known storage devices that the actuating drive for the transfer element is provided above the transport surface or the transport plane. As a result, the accessibility, in particular also the optical accessibility, of the transport surface for an opto-electrical device that is controlling and/or monitoring the storage device is restricted. As a result, an adjustment of the transfer element, and hence a change of the receiving or storage capacity of the storage device, is not possible independently of controlling or regulating of the transport elements, in particular of controlling or regulating of the conveying speed of the transport elements.
Storage devices are also known (DE 20 2004 012 848 U1) that each consist of two transport belts having opposed transport directions that are parallel to, but at a considerable distance from, one another and that are driven to endlessly circulate, and a transfer unit, acting between the transport belts, that can be displaced in the linear direction of the transport belts in order to change the storage or receiving capacity of the storage device and with which the products can be guided from the transport belt forming the product entry to the transport belt forming the product exit. To this end, the transfer unit comprises, for example, a transport element that is driven to rotate about a vertical axis and that takes the products from the one transport belt and moves them to the other transport belt. One of the disadvantages of these known storage devices is that the storage sections that are formed by the two transport elements between the transfer device and the product entry or product exit have a relatively narrow width compared to the maximum diameter of the products. This means that achieving a given maximum storage capacity requires a relatively long overall length of the storage device. A further disadvantage is that when the storage sections are configured with a width greater than the diameter of the products, the transfer device can only be realized with great design complexity. Yet another difficulty is that a trouble-free transfer of the products from the transport element that forms the product entry to the transport element that forms the product exit is not guaranteed.